For a machine comprising at least one electric motor, a retard torque and/or power can be used to slow motion of the machine. Slowing the machine can depend upon a plurality of factors such as machine weight, a slope of a path of the machine, and/or the available retard torque and/or power. Often, machines can be operated with a retard torque and/or power control that does not allow a sufficient control margin in certain situations.
U.S. Pat. No. 6,299,263 (Uematsu), which is incorporated by reference herein in its entirety, allegedly recites an “automatic retarder controller for a vehicle, which can prevent overheating, and can more precisely control the vehicle speed to remain constant. For this purpose, in the automatic retarder controller which is mounted on a load-carrying vehicle together with a cooled retarder (31) for exerting a braking force in response to a driving signal, and which automatically controls the driving signal so that the slope descending speed of the vehicle remains nearly constant, a detector for detecting the loading weight of the vehicle is included, and the controller impresses the gain corresponding to the detected loading weight upon the driving signal while the controller controls the vehicle speed to remain constant.” See Abstract.
U.S. Pat. No. 6,249,733 (Smith), which is incorporated by reference herein in its entirety, allegedly recites an “automatic control for operating an engine retarder, service brakes, and an automatic transmission associated with earth moving equipment is provided. The automatic control monitors engine speed and responsively produces control signals to maintain engine speed within predetermined limit.” See Abstract.
U.S. Pat. No. 6,150,780 (Young), which is incorporated by reference herein in its entirety, allegedly recites torque “is distributed by calculating first and second torque commands using a requested torque and a ratio of speeds of first and second wheels and limiting them in accordance with respective torque command approved ranges and approved change rates; converting the limited torque commands to horsepower commands and limiting them in accordance with respective horsepower command approved ranges and approved change rates; and converting the limited horsepower commands to present torque commands. Maximum horsepower available is determined by using an engine speed to determine a nominal amount of available horsepower; applying a desired load status signal and an actual engine load status signal to a proportional-integral A regulator; and using the nominal amount of available horsepower and an output signal of the regulator to determine the maximum amount of available horsepower. Thermal protection is provided by obtaining component temperatures of a plurality of components; normalizing each component temperature; obtaining a normalized drive system temperature by determining a maximum value of the normalized component temperatures; and comparing the normalized drive system temperature with at least one predetermined maximum normalized temperature and using a result of the comparison to determine whether a corrective action is needed. A truck is started on an incline by determining whether its speed is below a predetermined speed limit, a service brake is applied, and an accelerator pedal is depressed, and, if so, permitting a propulsion torque to build without requiring an operator override action.” See Abstract.